Depressed in the summer? You are not alone
The arrival of summer is usually greeted with joy. Many people welcome longer days, more sunshine and more intense light. They also revel in wearing less clothing and being able to spend more time outdoors. In short, most people enjoy the seasonal changes of summer – except for a largely silent minority who absolutely dread it.
Yes, it’s true. Some people, far from being buoyed by the light-filled days, experience agitation, sleep disturbances, anxiety and appetite changes. They generally eat less, sleep less, and lose weight. And they’re irritable. The condition is a sort of antipode to the better-known winter version of Seasonal Affective Disorder (SAD), during which individuals sleep more, gain weight and crave high-carb foods.
The summer-onset depression is thought to affect 1 % of the population, versus the 5% for its winter counterpart. In its most severe form, the summer SAD can be a serious risk factor for suicide, as agitated, anxious people are more motivated to do something about it than their hibernating winter counterparts.
Summer depression was first recognized clinically in 1986. Back then, it was thought to relate primarily to the experience of extreme heat and humidity. It was thought that air-conditioning, cold showers, swimming in lakes or heading for cooler climates would alleviate symptoms. While these measures do help, they appear not to have the same efficacy as the natural-spectrum light box for winter depression.
Dr. Norman Rosenthal, a clinical professor of psychiatry at Georgetown University Medical School, theorizes that it may be the intensity of the light itself which provokes the condition. One of his patients vividly describes the experience as a "feeling like the light is cutting though me like a knife." Another psychiatrist studying the phenomenon, Dr. Alfred Lewy at Oregon Health & Science University in Portland, suspects that the cause may be a disturbed circadian rhythm in the summer. Instead of cueing to dawn, the longer daylight is causing some vulnerable people to cue to dusk. Cueing to dusk shortens the typical body clock and delays a person's sleep-wake cycle. This mismatch, theorizes Lewy, may be triggering depression.
Presumably, the “cueing” is the body’s alignment to the “beginning” of its diurnal cycle. By cueing at dusk instead of at dawn, the body is energized at night, having begun its day cycle at sundown. This would naturally lead to insomnia and exhaustion. During the day, feelings of depression could be expected as the body expects to sleep. The fatigue from a restless night would only exacerbate the condition.
An interesting question to pursue would be what causes the body to cue at dusk and not at dawn? Very few people in our modern world actually experience dawn in the summer. Since it can come as early as 4:30 AM, most people sleep right through it, perhaps depriving the body of the cue it needs.